An acoustic horn is a structure which utilises outwardly flaring rigid walls to provide an expanding passage for acoustic energy between a throat entrance and a mouth exit. The acoustic horn is stimulated by a source driver unit which produces acoustic energy, and the acoustic horn then modifies and controls the acoustic energy.
The audio industry has spent many decades on the design of acoustic horns with defined areas of coverage. For instance, 90° in a horizontal plane by 40° in a vertical plane, or 60° by 40°, and so on. Generically they are called constant directivity horns.
A constant directivity acoustic horn generally comprises a throat entrance and a mouth exit joined by continuous rigid walls. A throat section extends away from the throat entrance and then extends to a feeder section which is rectangular in transverse cross-sectional shape. Acoustical energy is coupled thereto from a source driver unit connected to the throat entrance. The feeder section has an expanding transverse area formed by a first pair of walls which diverge outwardly from each other, and a second pair of walls which are substantially parallel and joined to the first pair.
The mouth exit of the horn has a rectangular configuration and is formed by a bell section having walls which diverge outwardly from the end of the feeder section, there being a first pair of diverging walls, and a second pair of diverging walls which join with the first pair of walls of the bell section along the edges to form an integral unit. The walls of the bell section may be flared outwardly an additional amount at a transverse plane immediately adjacent to the mouth to provide improved control of the radiation of acoustic energy.
In general the divergence angle between the first pair of walls and between the second pair of walls of the bell section determines the dispersion angle of the acoustical energy. A feature of this geometry is that the side profile view and top profile view angles and the dimensions of the mouth can be varied independently in order to obtain specified outcomes.
Many shapes of constant directivity horns have been evolved over the years to try to achieve a more uniform coverage. Initial attempts were by Olsen with multi-cellular horns, Klipsch (U.S. Pat. No. 2,537,141) with radial sectorial, Keele (U.S. Pat. No. 4,071,112) with the concept of outer flanges, Henricksen et al (U.S. Pat. No. 4,187,926) with a design “in reverse” (Manta Ray), Keele again (U.S. Pat. No. 4,308,932) with profiles specified by a formula, Gunness (U.S. Pat. No. 4,685,532) with throat vanes (pseudo horns). Most of these shapes (e.g. the Manta Ray) which have evolved to meet the need for uniform coverage (directivity control) have other disadvantages, for example, an irregular on-axis frequency response.
It is an object of the present invention to provide an improved constant directivity horn and/or horn component.
It is a further object of the present invention to provide a horn and/or horn component that provides improved directivity control in the high frequency ranges.